KR20010049615A - Granules based on pyrogenic titanium dioxide, a process for preparing them and their use - Google Patents

Abstract

PURPOSE: Pyrogenic titanium dioxide granulates are provided which are useful as catalyst supports. CONSTITUTION: Such granulates based on pyrogenic titanium dioxide(TiO2) has an average particle diameter of 10 to 150 microns, a BET surface area of 25 to 100 m¬2/g, a pH of 3 to 6 and a tamped density of 400 to 1200 g/l. The granulates are obtainable by dispersing titanium dioxide into water and spray-drying the resulting dispersion, followed by salinization. The silanized granulates have an average particle diameter of 10 to 160 microns, a BET surface area of 15 to 100 m¬2/g, a pH of 3.0 to 9.0, a tamped density of 400 to 1200 g/l, and a carbon content of 0.3 to 12.0 wt%.

Description

Pyrogenic titanium dioxide granules, preparation method and use thereof {Granules based on pyrogenic titanium dioxide, a process for preparing them and their use}

The present invention provides pyrogenic titanium dioxide-based granules, a method for preparing the same, and uses thereof.

Pyrogenic titanium dioxide is characterized by high temperature and combustion hydrolysis [Ullmanns Enzyklopadie der technischen Chemie, 4th edition, vol. 21, by a page 464 (1982)] it is known which can be prepared from TiCl _4.

Pyrogenic titanium dioxide is characterized by extremely fine particles, high surface area (BET), high purity, spherical particles and lack of pores. Due to these properties, pyrogenic titanium dioxide is increasingly being considered as a catalyst support [Dr. Koth et al., Chem. Ing. Techn. 52, 628 (1980). In this application, the pyrogenic titanium dioxide is formulated in a mechanical manner using, for example, a tablet press.

Accordingly, it is an object to produce spray-dried granules of pyrogenic titanium dioxide that can be used as catalyst support.

The present invention provides an exothermic dioxide having physico-chemical properties with an average particle diameter of 10 to 150 μm, a BET surface area of 25 to 100 m 2 / g, a pH of 3 to 6 and a compressive density of 400 to 1,200 g / l. Titanium-based granules are provided.

Granules according to the invention can be prepared by dispersing pyrogenic titanium dioxide in water and spray-drying.

The present invention also has an average particle diameter of 10 to 160 µm, a BET surface area of 15 to 100 m 2 / g, a pH of 3.0 to 9.0, a compressive density of 400 to 1,200 g / l and a carbon content of 0.3 to 12.0% by weight. It provides a pyrogenic titanium dioxide-based granules having phosphorus physico-chemical properties.

Granules according to the invention can be prepared by dispersing pyrogenic titanium dioxide in water, spray-drying and silanizing the product. Halogenated silanes, alkoxysilanes, silazanes and / or siloxanes are used for silanization.

In particular as halogenated silanes the following materials can be used:

Halogenated organosilanes of the form X ₃ Si (C _n H _{2n + 1} ), wherein X is Cl or Br and n is 1 to 20,

Halogenated organosilanes of the form X ₂ (R ′) Si (C _n H _{2n + 1} ), wherein X is Cl or Br, R 'is alkyl and n is 1 to 20,

Halogenated organosilanes of the form X (R ′) ₂ Si (C _n H _{2n + 1} ), wherein X is Cl or Br, R 'is alkyl and n is 1 to 20,

Halogenated organosilanes of the form X ₃ Si (CH ₂ ) _m -R 'wherein X is Cl or Br, m is 0 or 1 to 20, and R' is alkyl, aryl (e.g., -C ₆ H ₅ ), -C ₄ F ₉ , -OCF ₂ -CHF-CF ₃ , -C ₆ F ₁₃ , -O-CF ₂ -CHF ₂ , -NH ₂ , -N ₃ , -SCN, -CH = CH ₂ , -OOC (CH ₃ ) C = CH ₂ , -OCH ₂ -CH (O) CH ₂ , -NH-CO-N-CO- (CH ₂ ) ₅ , -NH-COO-CH ₃ , -NH-COO -CH ₂ -CH ₃ , -NH- (CH ₂ ) ₃ Si (OR) ₃ or -S _x- (CH ₂ ) ₃ Si (OR) ₃ ),

Halogenated organosilanes of the formula (R) X ₂ Si (CH ₂ ) _m -R 'wherein X is Cl or Br, R is alkyl, m is 0 or 1-20, and R' is alkyl, aryl (E.g., -C ₆ H ₅ ), -C ₄ F ₉ , -OCF ₂ -CHF-CF ₃ , -C ₆ F ₁₃ , -O-CF ₂ -CHF ₂ , -NH ₂ , -N ₃ , -SCN, -CH = CH ₂ , -OOC (CH ₃ ) C = CH ₂ , -OCH ₂ -CH (O) CH ₂ , -NH-CO-N-CO- (CH ₂ ) ₅ , -NH-COO -CH ₃ , -NH-COO-CH ₂ -CH ₃ , -NH- (CH ₂ ) ₃ Si (OR) ₃ or -S _x- (CH ₂ ) ₃ Si (OR) ₃ ), and

(R) halogenated organosilanes of the form ₂ XSi (CH ₂ ) _m -R 'wherein X is Cl or Br, R is alkyl, m is 0 or 1-20, and R' is alkyl, aryl ( For example, -C ₆ H ₅ ), -C ₄ F ₉ , -OCF ₂ -CHF-CF ₃ , -C ₆ F ₁₃ , -O-CF ₂ -CHF ₂ , -NH ₂ , -N ₃ ,- SCN, -CH = CH ₂ , -OOC (CH ₃ ) C = CH ₂ , -OCH ₂ -CH (O) CH ₂ , -NH-CO-N-CO- (CH ₂ ) ₅ , -NH-COO- CH ₃ , -NH-COO-CH ₂ -CH ₃ , -NH- (CH ₂ ) ₃ Si (OR) ₃ or -S _x- (CH ₂ ) ₃ Si (OR) ₃ ).

In particular, the following materials may be used as the alkoxysilane:

Organosilanes of the (RO) ₃ Si (C _n H _{2n + 1} ) type, wherein R is alkyl and n is 1-20,

Organosilanes of the form R ′ _x (RO) _y Si (C _n H _{2n + 1} ), wherein R is alkyl, R 'is alkyl, n is 1-20, x + y is 3, and x is 1 or 2, y is 1 or 2),

Organosilanes of the type (RO) ₃ Si (CH ₂ ) _m -R 'wherein R is alkyl, m is 0 or 1-20, and R' is alkyl, aryl (e.g., -C ₆ H ₅ ), -C ₄ F ₉ , -OCF ₂ -CHF-CF ₃ , -C ₆ F ₁₃ , -O-CF ₂ -CHF ₂ , -NH ₂ , -N ₃ , -SCN, -CH = CH ₂ ,- OOC (CH ₃ ) C = CH ₂ , -OCH ₂ -CH (O) CH ₂ , -NH-CO-N-CO- (CH ₂ ) ₅ , -NH-COO-CH ₃ , -NH-COO-CH ₂ -CH ₃ , -NH- (CH ₂ ) ₃ Si (OR) ₃ or -S _x- (CH ₂ ) ₃ Si (OR) ₃ ), and

Organosilanes of the formula (R ") _x (RO) _y Si (CH ₂ ) _m -R 'wherein R" is alkyl, x + y is 3, x is 1 or 2, y is 1 or 2 R 'is alkyl, aryl (e.g., -C ₆ H ₅ ), -C ₄ F ₉ , -OCF ₂ -CHF-CF ₃ , -C ₆ F ₁₃ , -O-CF ₂ -CHF ₂ , -NH ₂ , -N ₃ , -SCN, -CH = CH ₂ , -OOC (CH ₃ ) C = CH ₂ , -OCH ₂ -CH (O) CH ₂ , -NH-CO-N-CO- (CH ₂ ) ₅ , -NH-COO-CH ₃ , -NH-COO-CH ₂ -CH ₃ , -NH- (CH ₂ ) ₃ Si (OR) ₃ or -S _x- (CH ₂ ) ₃ Si (OR) ₃ ).

Preferably, silane Si 108 [(CH ₃ O) ₃ -Si-C ₈ H ₁₇ ] trimethoxyoctylsilane can be used as the silane agent.

In particular, the following materials may be used as silazane:

Silazanes in which R is alkyl and R 'is alkyl or vinyl, and for example hexamethyldisilazane.

In particular, the following materials can be used as the siloxane.

Cyclic polysiloxanes of type D 3, D 4 or D 5, for example octamethylcyclotetrasiloxane of the formula

, or

Polysiloxane or Silicone Oil of Formula

In the above formula,

m is 0, 1, 2, 3 to ∞,

n 'is 0, 1, 2, 3 to ∞,

u is 0, 1, 2, 3 to ∞,

Y is CH ₃ , H or C _n H _{2n + 1} where n is 1 to 20,

Y 'is Si (CH ₃ ) ₃ , Si (CH ₃ ) ₂ H, Si (CH ₃ ) ₂ OH, Si (CH ₃ ) ₂ (OCH ₃ ) or Si (CH ₃ ) ₂ (C _n H _{2n + 1} ), Where n is 1 to 20,

R is alkyl, aryl, (CH ₂ ) _n -NH ₂ or H,

R 'is alkyl, aryl, (CH ₂ ) _n -NH ₂ or H,

R ″ is alkyl, aryl, (CH ₂ ) _n -NH ₂ or H,

R ′ ″ is alkyl, aryl, (CH ₂ ) _n -NH ₂ or H.

The carbon content of the granules according to the invention may be 0.3 to 12.0% by weight.

The aqueous dispersion may have a concentration of 3 to 25% by weight titanium dioxide.

Organic auxiliary materials can be added to the dispersion to increase the stability of the dispersion and to improve particle morphology after spray-drying.

The following auxiliary substances such as polyhydric alcohols, polyethers, fluorinated hydrocarbon-based surfactants, or alcohols can be used.

Spray-drying may be carried out at a temperature of 200 to 600 ° C. Spinning disc atomizers or nozzle atomizers may be used.

The silanization can be carried out using halogenated silanes, alkoxysilanes, silazanes and / or siloxanes described above, wherein the silanizing agents can optionally be dissolved in organic solvents such as, for example, ethanol.

Preferably, silane Si 108 [(CH ₃ O) ₃ -Si-C ₈ H ₁₇ ] trimethoxyoctylsilane can be used as the silane agent.

The silanization may be carried out by spraying the silanizing agent on the granules at room temperature and then heat treating the mixture at 105 to 400 ° C. for 1 to 6 hours.

An alternative to the silanization of the granules can be carried out by treating the granules with a silanizing agent in the form of steam and then heat treatment at 200 to 800 ° C. for 0.5 to 6 hours.

The heat treatment can be carried out under a protective gas, for example nitrogen.

The silanization can be carried out continuously or batchwise in a heatable mixer and dryer having a spray device. Suitable devices can be, for example, plow bar mixers, disk dryers, fluidized bed dryers or mobile bed dryers.

The physico-chemical parameters of the granules, such as specific surface area, particle size distribution, compression density and pH, can be modified within the ranges given above by modifying the materials used and the conditions used during spraying, heating and silanization at constant temperature.

Titanium dioxide according to the invention has the following advantages:

Flow conditions are better than non-spray-dried titanium dioxide.

Incorporation into the organic system is easier.

Dispersion is easier

No additional auxiliary material is required for the granulation.

The titanium dioxide granules according to the invention have a constant particle size, unlike non-spray-dried titanium dioxide, which does not have a constant agglomerate size.

The titanium dioxide granules according to the invention can be handled in a dust-free manner.

Higher compression densities result in lower packaging costs for transportation.

The titanium dioxide granules according to the present invention can be used as catalyst support.

Non-spray-dried titanium dioxide is not suitable for this purpose, for example, because it is carried out with a fluidized bed.

The granules according to the invention can be used as a support for catalysts and also as sunscreens in cosmetics, as abrasives and varnishes in silicone rubbers, color powders, lacquers and colorants, and as raw materials for glass and porcelain production.

Example

Titanium dioxide P 25 having the following physical-chemical properties is used as pyrogenic titanium dioxide. This is described in the series of Pigments, no., 56 "Hochdisperse nach dem Aerosilverfahren, 4th edition, February 1989, Degussa AG".

Titanium Dioxide P25 CAS no. 13463-67-7 Underwater Hydrophilic Appearance Crispy white powder BET surface area ¹⁾ (㎡ / g) 50 ± 15 Average size of initial particles (nm) 21 Compression Density ²⁾ (g / ℓ) About 100 Specific gravity ¹⁰⁾ g / ℓ About 3.7 ³⁾ Loss (%) when drying out of supply device (2 hours at 105 ℃) 〈1.5 ^{4) 7)} Loss during combustion (2 hours at 1000 ℃) < 2 pH (in 4% aqueous dispersion) 3 to 4 SiO ₂ ⁸⁾ 〈0.2 Al ₂ O ₃ ⁸⁾ 〈0.3 Fe ₂ O ₃ ⁸⁾ 〈0.01 TiO ₂ ⁸⁾ 〉 99.5 ZrO ₂ ⁸⁾ - HfO ₂ ⁸⁾ - HCl ⁹⁾ 〈0.3 Sieve residue ⁶⁾ (%) (Mocker's method, 45 μm) <0.05 1) In accordance with DIN 66131 2) In accordance with DIN ISO 787 / XI, JIS K 5101/18 (without sieve) 3) In accordance with DIN ISO 787 / II, ASTM D 280, JIS K 5101/21 4) DIN 55921, 5) DIN ISO 787 / IX in accordance with ASTM D 1208, JIS K 5101/23; ASTM D 1208; 6) DIN ISO 787 / XVIII in accordance with JIS 5101/24; According to JIS K 5101/20 7) For materials dried for 2 hours at 105 ° C 8) For materials burned for 2 hours at 1000 ° C 9) The HCl content is the loss during combustion. 10) Measure with air comparative density vessel

Titanium dioxide is prepared by spraying a volatile titanium compound into an oxyhydrogen flame formed from hydrogen and air. In most cases, titanium tetrachloride is used. The material is hydrolyzed under the influence of water produced during the oxyhydrogen gas reaction to produce titanium dioxide and hydrochloric acid. After leaving the flame, titanium dioxide is introduced into a so-called condensation zone where titanium dioxide initial particles and initial aggregates are formed. As a kind of aerosol, the product present in this step is separated from the gaseous companion materials in the precipitator and then worked up with wet hot air.

The particle size of titanium dioxide can vary by changing reaction conditions such as, for example, the temperature of the flame, the production of hydrogen or oxygen, the amount of titanium tetrachloride, the residence time in the flame, or the length of the condensation zone.

The BET surface area is measured using nitrogen according to DIN 66 131.

Compression volume is measured by a method similar to that described in ASTM D 4164-88.

Device: Compression volumeometer STA V 2003 from Engelsmann Co., according to DIN 53194, para 5.2 b-f, 250 ml measuring cylinder graduated every 2 ml, weighing with a maximum error range of ± 0.1 g.

Take a measurement

Set the calculator up to 1000 strokes on the compression volumetric meter.

The weight of the measuring cylinder is measured.

Fill the measuring cylinder with granules below the 250 ml scale.

Record the weight (± 0.1 g).

The measuring cylinder is clamped in the compression volumeometer and the device is operated.

At the end of compression → the device stops automatically after 1000 strokes.

Read the volume up to 1 ml accurately.

Calculation

E: weight of granules (g)

V: read volume (ml)

W: water content (% by weight) (measured according to test guideline P001)

The pH is measured in 4% aqueous dispersion, in the case of hydrophobic catalyst support in water: ethanol 1: 1.

Preparation of Granules According to the Invention

Pyrogenic titanium dioxide is dispersed in fully deionized water. Use a dispersing device that operates according to the rotor / stator principle. The resulting dispersion is spray-dried. Precipitation of the final product is achieved using a filter or a dust collector.

Spray-dried and optionally heated granules are first introduced into a mixer to be silanized, first with optional mixing, optionally with water and then with a silanizing agent. After the spraying process is completed, the mixture is continued for 15-30 minutes, and then the mixture is heated at 100-400 ° C. for 1-4 hours at constant temperature.

The water used can be acidified, for example with hydrochloric acid until the pH is between 7 and 1. The silaning agent used can be dissolved in a solvent, for example ethanol.

Data for Spray-Drying Aqueous TiO ₂ P25 Dispersion Example Quantity of H ₂ O [kg] Quantity of TiO ₂ P25 [kg] Used atomizer Speed of spray disk [rpm] Working temperature [℃] Outlet air temperature [℃] Sedimentation One 10 1.5 disk 35000 345 100 Dust Collector 2 10 1.5 disk 45000 370 105 Dust Collector 3 10 1.5 disk 20000 350 95 Dust Collector 4 10 2.5 disk 15000 348 100 Dust Collector 5 100 15 2-fluid nozzle --- 445 130 filter 6 100 15 disk 10000 450 105 filter 7 10 2.5 disk 20000 348 105 Dust Collector 8 10 1.5 disk 15000 348 105 Dust Collector 9 10 2.5 disk 35000 300 105 Dust Collector

Physical-Chemical Data of Spray-Dried Products Example BET surface area [㎡ / g] Compression Density [g / ℓ] pH d ₅₀ value (Cilas) [μm] Loss on Drying [%] Loss on combustion [%] One 51 641 3.9 14.6 0.9 0.9 2 50 612 3.7 10.6 0.8 1.0 3 52 680 3.5 25.0 0.8 1.0 4 51 710 3.7 43.6 0.8 1.2 5 52 660 4.0 17.1 0.9 0.9 6 53 702 3.9 27.5 0.9 0.9 7 50 708 3.5 26.7 1.1 0.6 8 53 696 3.9 30.1 1.0 0.9 9 49 640 3.7 16.0 0.7 0.8

Data on Hydrophobic Titanium Dioxide Granules According to Example 6 Example Quantity of P25 / 7 [kg] Hydrophobic agent Amount of hydrophobic agent [kg] Quantity of H ₂ O [kg] Constant temperature [℃] Heating time [hour] 10 2 Si 108 0.2 0.05 120 2 11 2 Si 108 0.3 0.05 120 2 12 3.15 Silicone oil 0.2 0 350 2 13 3.15 Silicone oil 0.3 0 350 15

Physico-chemical Data of Hydrophobized Titanium Dioxide Granules According to Example 6 Example BET surface area [㎡ / g] Carbon content [%] Compression Density [g / ℓ] pH Loss on drying [%] Loss on combustion [%] d ₅₀ value (Cilas) [μm] 10 36 3.9 848 3.1 0.2 4.2 29.8 11 30 5.5 873 3.2 0.4 6.1 28.7 12 32 2.1 768 3.6 0 1.9 30.2 13 25 3.3 883 3.9 0 4.4 28.1

According to the invention it is possible to produce spray-dried granules of pyrogenic titanium dioxide which can be used as catalyst support.

Claims (5)

Pyrogenic titanium dioxide-based granules having physico-chemical properties with an average particle diameter of 10 to 150 μm, a BET surface area of 25 to 100 m 2 / g, a pH of 3 to 6, and a compressive density of 400 to 1,200 g / l . A process for producing the granules according to claim 1, characterized in that the pyrogenic titanium dioxide is dispersed in water and spray dried. Physical particles having an average particle diameter of 10 to 160 µm, a BET surface area of 15 to 100 m 2 / g, a pH of 3.0 to 9.0, a compressive density of 400 to 1,200 g / l, and a carbon content of 0.3 to 12.0% by weight; Pyrogenic titanium dioxide granules having chemical properties. A process for producing the granules according to claim 3, characterized in that the pyrogenic titanium dioxide is dispersed in water, spray-dried and then silanized. Use of the granules according to claims 1 or 3 as catalyst support and also as sunscreen in cosmetics, as abrasives and varnishes in silicone rubbers, color powders, lacquers and colorants, and as raw materials for the production of glass and ceramics.